Temperature dependent water transport mechanism in gas diffusion layers revealed by subsecond operando X-ray tomographic microscopy

The product water of polymer electrolyte fuel cells (PEFCs) has to pervade the gas diffusion layer (GDL) and can lead shortages educt pathways catalyst hence significant performance losses. Here we report on efforts made enable subsecond submicron operando X-ray tomographic microscopy (XTM) over a wide range cell operating temperatures. short XTM scan times allow quantify contributions capillary-fingering phase-change-induced flow overall transport inside cathode GDL at two different temperatures 40 °C 80 during current ramp-up process. results suggest that dominates initial increase saturation levels typical automotive PEFC about °C, whereas driven development from beginning stagnating stage °C.